The present invention relates to an airbag apparatus, and specifically, it relates to an airbag apparatus for a driver""s seat. More particularly, it relates to an airbag apparatus having an improved inflator structure.
As is well known, an airbag apparatus for a driver""s seat is arranged at the center in a steering wheel. When a vehicle encounters an emergency, such as a collision, an inflator is operated to inflate the airbag.
This airbag apparatus for a driver""s seat generally comprises a plate base-member which is called a retainer, an inflator, an airbag, and a module cover, as main components. The center of the retainer is provided with an insertion hole for the inflator into which a proximal side of the inflator is inserted.
The inflator is provided with a flange-like fitting piece, which may be simply referred to as a flange below, projecting from the side face of the inflator for attaching and fixing the inflator to the retainer.
The flange abuts against the periphery of the inflator insertion hole. The inflator comprises a casing which is filled with a gas generant, and a gas outlet disposed on the outer peripheral surface in the head side of the inflator, wherein the gas generant is ignited by an igniter to generate gas which is ejected from the gas outlet.
The rear end of the airbag is provided with an opening which is superposed on the periphery of the inflator insertion hole. A ring-fitting member for fitting the airbag, which may be simply referred to as a ring below, is arranged so as to hold the periphery of the opening, and the ring is fixed thereto with bolts and nuts or rivets. The periphery of the opening in the airbag is clamped between the ring and the periphery of the inflator insertion hole in the retainer, so that the airbag is fixed to the retainer.
In such an airbag apparatus, the flange or fitting piece is indispensable for the inflator for fixing the inflator to the retainer. However, the flange is generally arranged to the side face of the inflator, etc., by welding, etc., so that the operation is complicated while manufacturing cost increases. In such an airbag apparatus, there may be a case in that the flange is omitted, and a holding member, such as a bracket, for holding the inflator is newly and additionally required instead of the flange. In this situation, with increasing the number of parts, assembling operation of the airbag apparatus becomes complicated, and thereby also increasing the manufacturing cost.
It is an object of the present invention to provide an airbag apparatus in which an inflator can be attached to a retainer by solving such conventional problems without arranging a new member for holding the inflator to the retainer even when using an inflator without a fitting piece, such as a flange.
Further objects and advantages of the invention will be apparent from the following description of the invention.
An airbag apparatus according to the present invention comprises a base member or retainer, an airbag attached to the base member by an airbag-fitting member, an inflator for generating gas so as to inflate the airbag, and a module cover for covering the folded airbag, wherein the inflator has a smooth side face without a fitting piece projecting from the side face of the inflator. The inflator is fixed to the base member by the airbag-fitting member.
In the airbag apparatus according to the present invention, even when using the inflator without the fitting piece to the retainer, the inflator can be fixed to the retainer by the airbag-fitting member together with the airbag. Therefore, the process for providing the inflator with the fitting piece, such as a flange, is eliminated, and moreover, it is not necessary to provide the inflator with a new holding member to the retainer instead of such a fitting piece, so that the cost can be reduced.
In the airbag apparatus according to the present invention, preferably, the airbag is arranged on the front face of the base member, and the base member has an accommodating area projecting rearward for accommodating the inflator, wherein the airbag-fitting member has a capping portion for holding the inflator around the front face of the inflator, and the inflator is accommodated in the accommodating area and fixed to the base member by being held by the capping portion.
By such a structure, in the airbag apparatus according to the present invention, even when using the inflator without the fitting piece to the retainer, the inflator can be securely and easily fixed to the retainer without the holding member to the retainer replacing the fitting piece.
In the airbag apparatus according to present invention, preferably, the airbag is arranged on the front face of the base member which is provided with an accommodating member attached thereto and protruding rearward from the base member for accommodating the inflator, and the airbag-fitting member may include the capping portion for holding the inflator around the front face of the inflator. In such a case, the inflator is fixed to the face member by being accommodated in the accommodating member and held by the capping portion.
By such a structure, as the retainer of an airbag apparatus according to the present invention, a conventional retainer without the accommodating area for the inflator and having only an opening for receiving the inflator can be used. That is, on the rear face of such a conventional retainer, an accommodating member for accommodating the inflator is attached from the opening, and on the front face of the retainer, the airbag-fitting member having the capping portion for holding the inflator around the front face of the inflator is arranged, so that the inflator without the fitting piece can be securely fixed to the retainer as described above. Therefore, even when a conventional retainer is used, the inflator having no fitting piece to the retainer in itself can be securely fixed to the retainer.
In the airbag apparatus described above, a switch may be further disposed between the front face of the inflator and the front face of the module cover, and the switch may be supported by the capping portion of the airbag-fitting member.
By such a structure, when the module cover is made from a synthetic resin which is elastically deformable by pressing the front face thereof, for example, and when the switch, such as a horn switch, which is operable by pressing the front face of the module cover, is arranged between the front face of the inflator and the front face of the module cover, the switch can be supported by the capping portion of the airbag-fitting member, thereby improving the operability and the operating feeling of the switch.
In the airbag apparatus according to the present invention, the airbag-fitting member may be preferably connected to the front face of the airbag via a strap. In the airbag apparatus formed in such a manner, the strap is arranged such that one end of the strap is connected to the front face of the airbag along the peripheral face of the airbag while the other end is connected to the airbag-fitting member within the airbag. Therefore, the strap becomes restraining means for restraining the airbag configuration during inflation when the airbag is inflated by the gas ejection from the inflator.
That is, the strap has a predetermined length, and the front face of the airbag which is connected to the airbag-fitting member by the strap can not be separated therefrom by the strap for more than a predetermined distance when the airbag is inflated. Therefore, when the inflator is operated so as to eject gas and inflate the airbag in a vehicle cabin upon an emergency, such as a vehicle collision, the front face of the airbag can not be inflated over a predetermined amount, so that the side of the airbag is largely inflated outside the steering wheel due to a gas pressure, enabling a driver to be securely protected.
In the airbag apparatus according to the present invention, the module cover or an emblem may be attached to the front face of the airbag and the module cover or the emblem may be connected to the airbag-fitting member by a strap.
In this case, the module cover or the emblem is attached on the front face of the airbag along the external peripheral surface of the airbag, and on the front face of the airbag, an insertion hole for insertion of the strap is formed. One end of the strap inserted into the insertion hole is connected to the module cover or the emblem while the other end is connected to the airbag-fitting member within the airbag.
In the airbag apparatus formed in such a manner, when the airbag is inflated, the module cover or the emblem attached on the front face of the airbag moves toward a driver following the inflation of the airbag and the movement is stopped by the strap after a predetermined movement. Therefore, in the airbag apparatus formed in such a manner, the inflation of the front face of the airbag is restrained and the sides of the airbag are largely inflated outside the steering wheel due to a gas pressure, enabling the driver to be securely protected.